However, although sunitinib is generally very effective in shrinking tumors, the xenograft tumors formed by the 786-O VHL-/- cell line tend to be only mildly responsive to sunitinib treatment in mice [34,35], thus it raises the question whether VEGF is critical for 786-O VHL-/- cells to grow into tumor efficiently in mice. The gene discussed is VHL; the disease is neoplasm.